Alternatives to conventional thermal treatments in fruit-juice processing. Part 2: Effect on composition, phytochemical content, and physicochemical, rheological, and organoleptic properties of fruit juices

The combined effect of supercritical carbon dioxide and mild temperatures on pectin methylesterase inactivation in orange juice

Pectin methylesterase (PME) is the target-enzyme in orange juice processing, and its inactivation preserves the original juice's cloud, a valuable quality attribute for consumers. This study was primarily undertaken to evaluate the combination of supercritical carbon dioxide (SC-CO2) and mild temperatures on PME inactivation in the juice. Physicochemical and color parameters were also evaluated. Pressures (P) in the range of 74 to 351 bar, temperatures (T) between 33°C and 67°C, and holding times (t) varying from 20 to 70 min were tested using a central composite rotational design. Determination of PME activity, pH, titratable acidity, soluble solids, ratio, lightness, °hue and chroma in freshly extracted/raw and treated juice samples, and total color difference (TCD) between raw and treated juice were carried out. The percentage of PME reduction widely ranged from 13.7% to 91.8%. The variable P had a significant effect (p ≤ 0.05) on TCD and acidity variation. T exhibited a significant effect on the PME reduction, TCD, and soluble solids variation; however, t impacted on the soluble solids variation only. The interaction between P and t (P.t) affected the soluble solids and acidity variation, and T.t affected TCD. The combination of SC-CO2 and mild temperatures is potentially capable of inactivating PME in orange juice.

The Role of MMP-9 and MMP-9 Inhibition in Different Types of Thyroid Carcinoma

Matrix metalloproteinase-9 (MMP-9), one of the most investigated and studied biomarkers of the MMPs family, is a zinc-dependent proteolytic metalloenzyme whose primary function is degrading the extracellular matrix (ECM). It has been proved that MMP-9 expression elevates in multiple pathological conditions, including thyroid carcinoma. MMP-9 has a detectable higher level in malignant or metastatic thyroid tumor tissues than in normal or benign tissues and acts as an additional marker to distinguish different tumor stages because of its close correlations with clinical features, such as lymph node metastasis, TNM stage, tumor size and so on. Natural and non-natural MMP-9 inhibitors suppress its expression, block the progression of diseases, and play a role in therapy consequently. MMP-9 inhibitory molecules also assist in treating thyroid tumors by suppressing the proliferation, invasion, migration, metastasis, viability, adhesion, motility, epithelial-mesenchymal transition (EMT), and other risk factors of different thyroid cancer cells. In a word, discovering and designing MMP-9 inhibitors provide great therapeutic effects and promising clinical values in various types of thyroid carcinoma.

Differentiation of sea buckthorn syrups processed by high pressure, pulsed electric fields, ohmic heating, and thermal pasteurization based on quality evaluation and chemical fingerprinting

Introduction

Impact of processing on product characteristics, sustainability, traceability, authenticity, and public health along the food chain becomes more and more important not only to the producer but also to the customer and the trust of a consumer toward a brand. In recent years, the number of juices and smoothies containing so called super foods or fruits, which have been "gently pasteurized," has increased significantly. However, the term "gentle pasteurization" related to the application of emerging preservation technologies such as pulsed electric fields (PEF), high pressure processing (HPP) or ohmic heating (OH) is not clearly defined.

Methods

Therefore, the presented study investigated the influence of PEF, HPP, OH, and thermal treatment on quality characteristics and microbial safety of sea buckthorn syrup. Syrups from two different varieties were investigated under the following conditions HPP (600 MPa 4-8 min), OH (83°C and 90°C), PEF (29.5 kV/cm, 6 μs, 100 Hz), and thermal (88°C, hot filling). Analyses to test the influence on quality parameters like ascorbic acid (AA), flavonoids, carotenoids, tocopherols, antioxidant activity; metabolomical/chemical profiling (fingerprinting) via U-HPLC-HRMS/MS (here especially flavonoids and fatty acids); sensory evaluation, as well as microbial stability including storage, were conducted.

Results and discussion

Independent from the treatment, the samples were stable over 8 weeks of storage at 4°C. The influence on the nutrient content [Ascorbic acid (AA), total antioxidant activity (TAA), total phenolic compounds (TPC), tocopherols (Vit E)] was similar for all tested technologies. Employing statistical evaluation Principal Component Analysis (PCA) a clear clustering based on the processing technologies was observed. Flavonoids as well as fatty acids were significantly impacted by the type of used preservation technology. This was obvious during the storage time of PEF and HPP syrups, where enzyme activity was still active. The color as well as taste of the syrups were found to be more fresh-like for the HPP treated samples.

Enhancement of Wheat Seed Germination, Seedling Growth and Nutritional Properties of Wheat Plantlet Juice by Plasma Activated Water

Previous studies have shown the great potential of using plasma-activated water (PAW) on improving agriculture seed germination, however, information on the influence of PAW on crop plantlet juice remains scanty. In this research, the effect of PAW generated by atmosphere pressure Ar-O₂ plasma jet for 1-5 min on wheat seed germination, seedling growth and nutritional properties of wheat plantlet juice was investigated. Results revealed that all PAWs could enhance wheat seed germination and seedling growth in 7 days by improving the germination rate, germination index, fresh weight, dry weight and vigour index, and especially that PAW activated for 3 min (PAW-3) showed the best overall performance. In addition, the application of PAWs enhanced the nutritional properties of wheat plantlet juice from those grown for 14 days by improving total soluble solids, protein content, photosynthetic pigments, total phenolic content, antioxidant activity, enzyme activity, free amino acids and minerals content, and the best enhancement was also observed in PAW-3. It was concluded that PAWs would be an effective technique to enhance the growth and nutritional properties of crop sprouts, which could be served as functional foods in many forms.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s00344-022-10677-3.

Chestnut Lily Beverage (CLB) Processing Using Ultrasound-Assisted Nisin: Microbiota Inactivation and Product Quality

We evaluated the effects of ultrasound (US) and ultrasound combined with nisin (NUS) treatments on the properties of chestnut lily beverages (CLB) using conventional thermal pasteurisation (TP) as a control. After CLB samples were treated with US and NUS for 20, 40, or 60 min, the polyphenol oxidase activity (PPO), microbial inactivation effect, colour, pH value, total phenolic content, and antioxidant capacity of the CLB were observed. It was found that the inactivation rate of PPO in CLB after NUS treatment was higher than that in the US, indicating that NUS treatment aggravated PPO inactivation. Treatment time was important in the inactivation of microorganisms by US and NUS; NUS had a lethal synergistic lethal effect on microorganisms in CLB and when compared with US, NUS reduced changes in the CLB colour value. Notably, the total phenolic content and antioxidant capacity of the US- and NUS-treated CLB significantly increased relative to the TP group. These results that suggest NUS has a potential application value in the development of CLB because it reduces the risk of microorganism contamination and helps improve the quality of CLB. This study provides technical support and a theoretical basis for the improved production of CLB.

Citrus juice off-flavor during different processing and storage: Review of odorants, formation pathways, and analytical techniques

As the most widespread juice produced and consumed globally, citrus juice (mandarin juice, orange juice, and grapefruit juice) is appreciated for its attractive and distinct aroma. While the decrease of characteristic aroma-active compounds and the formation of off-flavor compounds are easy to occur in processing and storage conditions. This review provides a comprehensive literature of recent research and discovery on citrus juice off-flavor, primarily focusing on off-flavor compounds induced during processing and storage (i.e., thermal, storage, light, oxygen, package, fruit maturity, diseases, centrifugal pretreatment, and debittering process), formation pathways (i.e., terpene acid-catalyzed hydration, caramelization reaction, Maillard reaction, Strecker degradation, and other oxidative degradation) of the off-flavor compounds, effective inhibitor pathway to off-flavor (i.e., electrical treatments, high pressure processing, microwave processing, ultrasound processing, and chemical treatment), as well as odor assessment techniques based on molecular sensory science. The possible precursors (terpenes, sulfur-containing amino acids, carbohydrates, carotenoids, vitamins, and phenolic acids) of citrus juice off-flavor are listed and are also proposed. This review intends to unravel the regularities of aroma variations and even off-flavor formation of citrus juice during processing and storage. Future aroma analysis techniques will evolve toward a colorimetric sensor array for odor visualization to obtain a "marker" of off-flavor in citrus juice.

Protective Effect of Ultrasound-Processed Amazonian Sapota-do-Solimões (Quararibea cordata) Juice on Artemia salina Nauplii

Juice processing by non-thermal technology has been extensively studied, aiming at microbial inactivation and quality improvement. However, the knowledge about the possible toxic effects that those technologies can produce in foodstuffs due to the production of reactive oxygen species is still unknown. In this study, sapota-do-Solimões juice processed by ultrasound (2, 6, and 10 min) was evaluated by a toxicity test and protective effect through stress biomarkers (catalase, superoxide dismutase, and lipid peroxidation) using Artemia salina nauplii. The non-thermal processed juice was nontoxic to A. salina. However, the juice fibers imparted some damage to the animal’s body. The ultrasound-processed juice (2 and 6 min) decreased the A. salina mortality to 30% compared to the control assay with H2O2 where mortality was 80% after 48 h of exposure. However, after 72 h of exposure, the A. salina was entirely degraded by H2O2-induced toxicity. Furthermore, the catalase and superoxide dismutase presented the highest activity after A. salina was exposed to the unprocessed juice. Thus, sapota-do-Solimões juice processed by the ultrasound could promote a protective effect on A. salina, revealing this technology’s potential to enhance juice features without toxicity.

How to comprehensively improve juice quality: a review of the impacts of sterilization technology on the overall quality of fruit and vegetable juices in 2010-2021, an updated overview and current issues

Fruit and vegetable juices (FVJ) are rich in nutrients, so they easily breed bacteria, which cause microbial pollution and rapid deterioration of their quality and safety. Sterilization is an important operation in FVJ processing. However, regardless of whether thermal sterilization or non-thermal sterilization is used, the effect and its impact on the overall quality of FVJ are strongly dependent on the processing parameters, microbial species, and FVJ matrix. Therefore, for different types of FVJ, an understanding of the impacts that different sterilization technologies have on the overall quality of the juice is important in designing and optimizing technical parameters to produce value-added products. This article provides an overview of the application of thermal and non-thermal technique in the field of FVJ processing over the past 10 years. The operating principle and effects of various technologies on the inactivation of microorganisms and enzymes, nutritional and functional characteristics, physicochemical properties, and sensory quality of a wide range of FVJ are comprehensively discussed. The application of different combinations of hurdle technology in the field of FVJ sterilization processing are also discussed in detail. Additionally, the advantages, limitations, and current application prospects of different sterilization technologies are summarized.

Study of heat transfer coefficients and temperature distribution in a continuous flow pasteurizer with helical tubes using model fluids in laminar flow

Modeling of continuous pasteurization is useful for predicting time-temperature history of the product and lethality. The use of helical tubes in the heat exchangers and holding tube can simplify modeling in laminar flow due to the narrowing of the residence time distribution. To present this approach, three model fluids (water, 80% glycerol/water and 1% carboxymethylcellulose) were processed in 25 conditions in a pilot scale unit and the overall heat transfer coefficients of the heater, cooler and holding tube were correlated with Reynolds and Prandtl numbers. For heater and cooler, 3–7 parameters were needed for a fair adjustment, while in the holding tube an average value was obtained. Using these correlations, a simple unidimensional model was simulated to predict the time-temperature history and lethality distribution. Simulation examples for processing at 90 °C provided the F-value contribution of each step showing that this model can be useful for process analysis and design.

Non-conventional Stabilization for Fruit and Vegetable Juices: Overview, Technological Constraints, and Energy Cost Comparison

This study will provide an overview and a description of the most promising alternatives to conventional thermal treatments for juice stabilization, as well as a review of the literature data on fruit and vegetable juice processing in terms of three key parameters in juice production, which are microbial reduction, enzyme inactivation, and nutrient-compound retention. The alternatives taken into consideration in this work can be divided, according to the action mechanism upon which these are based, in non-conventional thermal treatments, among which microwave heating (MWH) and ohmic heating (OH), and non-thermal treatments, among which electrical treatments, i.e., pulsed electric fields (PEF), high-pressure processing (HPP), radiation treatments such as ultraviolet light (UVL) and high-intensity pulsed light (PL), and sonication (HIUS) treatment, and inert-gas treatments, i.e., the pressure change technology (PCT) and supercritical carbon dioxide (SC-CO2) treatments. For each technology, a list of the main critical process parameters (CPP), advantages (PROS), and disadvantages (CONS) will be provided. In addition, for the non-thermal technologies, a summary of the most relevant published result of their application on fruit and vegetable juices will be presented. On top of that, a comparison of typical specific working energy costs for the main effective and considered technologies will be reported in terms of KJ per kilograms of processed product.

On the Effect of Microwave Heating on Quality Characteristics and Functional Properties of Persimmon Juice and Its Residue

In this study, it was investigated whether integration of microwave-heating into the pretreatment step of persimmon juice processing allows the concomitant production of both functional juice and added-value solid residue from the Diospyros Kaki "Jiro" cultivar. In this direction, persimmon pulp was treated under three different microwave-heating conditions (0.7, 4.2, and 8.4 kJ/g) prior to enzymatic maceration and compared to the non-heated material. Irrespective of microwave energy employed, the proposed hybrid treatment was highly efficient in terms of juice yield (70% w/w). The mildest heating conditions resulted in juice and residue that were both of inferior quality. Intensification of the microwave energy reduced the microbial load of the juice up to 2-log without compromising the content in total soluble solids, sugars, and L-ascorbic acid. Under the most drastic conditions, the juice was enriched in gallic acid, polyphenols, and potent DPPH● scavengers, but its orange color faded and was more acidic. In parallel, the solid juice residue retained pro-vitamin A carotenoids (~278 µg retinol activity equivalents) and low-methoxy pectin (9 g/100 g DW). Overall, our findings can assist the efforts of the local juice processing industry to utilize persimmon fruits through energy-efficient technologies in a sustainable approach.

Effect of Alternative Preservation Steps and Storage on Vitamin C Stability in Fruit and Vegetable Products: Critical Review and Kinetic Modelling Approaches

Vitamin C, a water-soluble compound, is a natural antioxidant in many plant-based products, possessing important nutritional benefits for human health. During fruit and vegetable processing, this bioactive compound is prone to various modes of degradation, with temperature and oxygen being recognised as the main factors responsible for this nutritional loss. Consequently, Vitamin C is frequently used as an index of the overall quality deterioration of such products during processing and post-processing storage and handling. Traditional preservation methods, such as thermal processing, drying and freezing, are often linked to a substantial Vitamin C loss. As an alternative, novel techniques or a combination of various preservation steps ("hurdles") have been extensively investigated in the recent literature aiming at maximising Vitamin C retention throughout the whole product lifecycle, from farm to fork. In such an integrated approach, it is important to separately study the effect of each preservation step and mathematically describe the impact of the prevailing factors on Vitamin C stability, so as to be able to optimise the processing/storage phase. In this context, alternative mathematical approaches have been applied, including more sophisticated ones that incorporate parameter uncertainties, with the ultimate goal of providing more realistic predictions.

Impact of High-Pressure Processing on Antioxidant Activity during Storage of Fruits and Fruit Products: A Review

Fruits and fruit products are an essential part of the human diet. Their health benefits are directly related to their content of valuable bioactive compounds, such as polyphenols, anthocyanins, or vitamins. Heat treatments allow the production of stable and safe products; however, their sensory quality and chemical composition are subject to significant negative changes. The use of emerging non-thermal technologies, such as HPP (High Pressure Processing), has the potential to inactivate the microbial load while exerting minimal effects on the nutritional and organoleptic properties of food products. HPP is an adequate alternative to heat treatments and simultaneously achieves the purposes of preservation and maintenance of freshness characteristics and health benefits of the final products. However, compounds responsible for antioxidant activity can be significantly affected during treatment and storage of HPP-processed products. Therefore, this article reviews the effect of HPP treatment and subsequent storage on the antioxidant activity (oxygen radical absorbance capacity (ORAC) assay), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity assay, ferric reducing antioxidant power (FRAP) assay, 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging capacity assay or Trolox equivalent antioxidant capacity (TEAC) assay), and on the total phenolic, flavonoid, carotenoid, anthocyanin and vitamin contents of fruits and different processed fruit-based products.

An overview of different homogenizers, their working mechanisms and impact on processing of fruits and vegetables

Fruits and vegetables (F&V) are the second highest recommended foods, rich in antioxidants, vitamins and minerals, vital for building immunity against chronic diseases. F&V processing involves particle size reduction, for which different types of homogenizers, categorized as mechanical homogenizers, pressure homogenizers and ultrasonic homogenizers are used. The review discusses different types of homogenizers, their working mechanism, and application in F&V processing. Among mechanical homogenizers, knife mills are used for primary size reduction, ball mills for the micronization of dried F&V and rotor-stator homogenizers for emulsification. Use of the ultrasonic homogenizer is limited to extraction of bioactive compounds or as a pre-treatment for dehydration of F&V. High-pressure homogenizers are most widely used and reported due to the synergistic effect of homogenization and temperature increase, resulting in longer shelf-life and better physicochemical properties of the product. Additionally, the review also explains the effect of homogenization on the physicochemical, sensory and nutraceutical properties of the product.

Thermolabile essential oils, aromas and flavours: Degradation pathways, effect of thermal processing and alteration of sensory quality

Plant-based aroma chemicals, constituting the essential oils play a great role as the natural flavours and preservatives in the food industries. Many of these metabolites are susceptible to degradation under heat (i.e. thermolabile aroma chemicals) which may influence the organoleptic properties of the end-products e.g. essential oil, oleoresin, dry herb, tea and packaged juice. The current review identified in total 42 thermolabile aroma and/or flavour molecules belonging to monoterpenoids, sesquiterpenoids and phenolics. The probable pathway of their degradation and its promoting conditions were also described. Degradation pathways were categorized into five major classes including oxidation, C-C bond cleavage, elimination, hydrolysis and rearrangement. Numerous evidences were cited in support of the thermosensitivity of these phytochemicals under pyrolytic, thermal heating or gas chromatographic conditions. Various post-harvest processes involved in the manufacturing such as drying and distillation of the crops or thermal treatment of the food-products for storage were highlighted as the root cause of degradation. The influence of thermolabile aroma chemicals to maintain the sensory quality of the end-products such as citrus juices, floral oils and thermally cooked foods was discussed in detail. In the present article, detailed insight into the chemical and sensory aspects of thermosensitive aromas and flavours was provided, covering the period from 1990 up to 2020.

Phenolic composition, antioxidant capacity and physical characterization of ten blackcurrant (Ribes nigrum) cultivars, their juices, and the inhibition of type 2 diabetes and inflammation biochemical markers

The objective was to analyze the phenolic composition, antioxidant capacity, and physical characteristics of 10 blackcurrant cultivars, their juices, and the enzymatic inhibition of dipeptidyl peptidase-IV, α-amylase, α-glucosidase, nitric oxide synthase, and cyclooxygenase-2. Fruit masses ranged from 0.47 to 1.22 g and diameters from 7.42 to 14.42 mm. For the juices, pH ranged from 2.80 to 2.96, soluble solids from 11.33% to 17.5%, total acidity from 3.17 to 4.26 g/100 mL, and viscosity from 1.28 to 273.83 mPa·s. Total anthocyanins (TA) ranged from 1.81 to 5.48 mg eq cyanidin 3-O-glucoside/100 g, total polyphenols (TP) from 7.67 to 39.70 mg eq gallic acid/100 g, total condensed tannins from 3.24 to 7.76 g eq catechin/100 g, and antioxidant capacity from 219.24 to 499.26 μmol eq Trolox/100 g. Juices of the cultivars Coronet and Consort contained the highest levels of TA, TP, and antioxidants. Whistler cultivar contained high concentrations of major anthocyanins. Juices from all cultivars favorably inhibited the activities of enzymes used as surrogate biochemical markers for T2 diabetes and inflammation.

Microwave heating effect on total phenolics and antioxidant activity of green and mature coconut water

Coconut water (Cocos nucifera L.) from fruits of two ripening stages (green and mature) was used to perform microwave heat treatments. Three different heating conditions with maximum temperatures of 70, 80 and 90 °C were tested in three holding times (0, 2 and 4 min). The Total Phenolic Content (TPC) using the Folin-Ciocalteu method and ABTS radical scavenging capacity were evaluated for each combination of coconut fruit age, heating temperature and holding time. It was observed that green coconut water exhibited significant differences (p < 0.05) compared to mature coconuts in terms of TPC (46.03 and 69.16 mg GAE/L, respectively) and ABTS radical scavenging capacity (422.31 and 549.1 μmol TE/L, respectively). An increase in TPC (up to 23%) and antioxidant activity (up to 19%) was also observed with increasing temperature in the range of 70–90 °C. Green coconut water showed the largest increase in both TPC and antioxidant activity.

Effects of ultraviolet-C light-emitting diodes at 275 nm on inactivation of Alicyclobacillusacidoterrestris vegetative cells and its spores as well as the quality attributes of orange juice

Alicyclobacillus acidoterrestris is a thermoacidophilic, spore-forming bacillus. A. acidoterrestris and its spores can survive in pasteurized juices and cause microbial spoilage. In this work, the effects of ultraviolet-C light-emitting diodes at 275 nm on the inactivation of A. acidoterrestris vegetative cells and its spores in commercial pasteurized orange juice were studied. Meanwhile, the effects of ultraviolet-C light-emitting diodes on the quality attributes of the orange juice were also investigated. The quantities of A. acidoterrestris vegetative cells and its spores inoculated in orange juice were reduced by 6.04 and 2.49 log₁₀ CFU/mL after ultraviolet-C light-emitting diode treatment at 220 mJ/cm², respectively. The Weibull and Weibull plus tail models were satisfactorily fitted to estimate the reductions of A. acidoterrestris vegetative cells and its spores in orange juice, respectively. Physicochemical properties (pH, titratable acidity, total soluble solids, and clarity) of orange juice did not change significantly after exposure to ultraviolet-C light-emitting diodes. However, the total phenolic content of orange juice decreased with increasing fluence. In addition, ultraviolet-C light-emitting diode treatment at a higher fluence led to a noticeable color difference. These results indicate that ultraviolet-C light-emitting diode treatment has a potential application in the juice processing industry.

Application of microwave and ohmic heating for pasteurization of cantaloupe juice: microbial inactivation and chemical properties

BACKGROUND

Cantaloupe melon (Cucumis melo L.) is one of the most important dessert fruits and is cultivated in many countries of the world. The effects of microwave (400 and 800 W for 110 s), ohmic (100 and 200 V for 110 s) and conventional heating (27-75 °C for 30 min) treatments on inactivation of Escherichia coli, Salmonella Typhimurium, S. Enteritidis and Staphylococcus aureus pathogens; pH and degradation of vitamin C, β-carotene and phenolic compounds of cantaloupe juice were investigated.

RESULTS

As time passed, all of the treatments resulted in significant (P ≤ 0.05) decreases in the number of pathogens and vitamin C, β-carotene and phenolic compound content, whereas the pH of samples did not show significant changes. The mentioned parameters were more reduced by increasing the power, voltage and temperature of ohmic, microwave and conventional heating treatments, respectively. Comparison of the results for conventional heating with those of ohmic and microwave heating revealed that the complete inactivation time of pathogens by the two latter treatments was much shorter than that of the former. After 20 s, the effect of ohmic heating at 200 V on decreasing vitamin C content was significantly (P ≤ 0.05) higher than that of the other treatments. The amounts of β-carotene and phenolic compounds showed the most reduction under 800 W microwave treatment.

CONCLUSION

The results obtained for conventional, ohmic and microwave heating treatments indicated a higher degradation of β-carotene and phenolic compounds and a lower loss of vitamin C in the former. © 2019 Society of Chemical Industry.

Comparative Effects of Thermal, High Hydrostatic Pressure, and UV-C Processing on the Quality, Nutritional Attributes, and Inactivation of Escherichia coli, Salmonella, and Listeria Introduced into Tiger Nut Milk

HIGHLIGHTS

Thermal and nonthermal methods can support a 5-log CFU reduction of model bacteria introduced into tiger nut milk. Thermal treatment of tiger nut milk results in significant loss of protein, antioxidants, and quality properties. HHP or UV-C treatment of tiger nut milk retains quality and nutritional characteristics. HHP or UV-C are suitable for the pasteurization of tiger nut milk.

Optimization of Uruset Apple Vinegar Production Using Response Surface Methodology for the Enhanced Extraction of Bioactive Substances

In this study, the aim is to produce non-thermal vinegar by using red Uruset apples, which have high bioavailability among apple varieties. For this purpose, Uruset apple vinegar was produced and ultrasound at different times (2, 4, 6, 8 and 10 min) and different amplitudes (40%, 50%, 60%, 70%, and 80%); in addition, a 26 kHz frequency was applied to the samples. Total phenolic content (TPC), total flavonoid content (TFC), total antioxidant capacity (1,1-diphenyl- 2-picrylhydrazyl (DPPH) and cupric reducing antioxidant capacity (CUPRAC)), and color values were evaluated for the optimization of process conditions. At the same time, the differences between commercial apple vinegar (CV), pasteurized Uruset apple vinegar (PV), and a control (C) of untreated apple vinegar were investigated. Ultrasound treatment of Uruset apple vinegar was more successful for the enrichment of bioactive substances than the other samples. At the end of the study, the maximal optimization values for Uruset apple vinegar were 7.4 min and 62.2 amplitude. At the end of optimization, CUPRAC (0.69 mg TEAC/mL), DPPH (0.49 mg TEAC/mL), total flavonoid content (46.95 mg CE/L), and total phenolic content (124.25 mg GAE/L) were determined. As a result, ultrasound technology was successfully used for Uruset apple vinegar production.

Long-Term Effect on Bioactive Components and Antioxidant Activity of Thermal and High-Pressure Pasteurization of Orange Juice

The long-term effect of thermal pasteurization (TP) and high-pressure processing (HPP) of orange juices stored under refrigeration, on the bioactive components and antioxidant activity, was compared. Total phenolic content (TPC), flavonoid, anthocyanin, and carotenoid contents, the individual content of major phenolic components, and the antioxidant activity, were evaluated in TP- and HPP-treated juices over a 36-day period. At day 0, no significant differences in TPC, and a decrease in carotenoid content after both treatments, were observed. TP caused a decrease of flavonoid and anthocyanin contents, while HPP increased flavonoid content. Three major phenolic components were identified: apigenin-6,8-di-C-glucoside, naringenin-7-O-rutinoside, and hesperetin-7-O-rutinoside, the latter increasing ca. 45% immediately after HPP. During storage, a decrease in TPC, and in the anthocyanin and carotenoid contents of both treated juices was observed, with higher anthocyanin and phenolic contents in HPP juices. A significant increase of hesperetin-7-O-rutinoside content was observed in HPP juice. Both treatments caused a decrease (26% and 13%, respectively) of antioxidant activity. Most of the kinetic profiles followed zero-order patterns, with HPP juices showing a considerably higher half-life than TP ones. These results clearly demonstrate the advantages of HPP for orange juice preservation allowing, also, their nutritional benefits to be enhanced by increasing the content of some bioactive components.

Effect of low thermal pasteurization in combination with carvacrol on color, antioxidant capacity, phenolic and vitamin C contents of fruit juices

Mild thermal treatment in combination with natural antimicrobials has been described as an alternative to conventional pasteurization to ensure fruit juices safety. However, to the best of our knowledge, no study has been undertaken to evaluate what could be its effect on their color and nutritional value. This study therefore aimed at assessing how a low thermal pasteurization in combination with carvacrol could affect these parameters, with orange, pineapple, and watermelon juices as selected fruit juices. The experimental design used had levels ranging from 50 to 90°C, 0 to 60 μl/L, and 0 to 40 min for temperature, concentration of carvacrol supplemented, and treatment length, respectively. The only supplementation of fruit juices with carvacrol did not affect their color. In comparison with high thermal pasteurization (>70°C), a combined treatment at mild temperatures (50-70°C) better preserved their color, antioxidant capacity (AOC), and vitamin C content, and increased their total phenolic content (TPC). Globally, carvacrol supplementation had a positive impact on the TPC of thermally treated juices and increased the AOC of treated watermelon juice, which was the lowest of the three fruit juices. Mild heat treatment in combination with natural antimicrobials like carvacrol is therefore an alternative to limit the negative effects of conventional pasteurization on fruit juices quality.

Inactivation of Spoilage Yeasts by Mentha spicata L. and M. × villosa Huds. Essential Oils in Cashew, Guava, Mango, and Pineapple Juices

This study evaluated the efficacy of the essential oil from Mentha spicata L. (MSEO) and M. × villosa Huds. (MVEO) to inactivate Candida albicans, C. tropicalis, Pichia anomala and Saccharomyces cerevisiae in Sabouraud dextrose broth and cashew, guava, mango, and pineapple juices during 72 h of refrigerated storage. The effects of the incorporation of an anti-yeast effective dose of MSEO on some physicochemical and sensory characteristics of juices were evaluated. The incorporation of 3.75 μL/mL MSEO or 15 μL/mL MVEO caused a ≥5-log reductions in counts of C. albicans, P. anomala, and S. cerevisiae in Sabouraud dextrose broth. In cashew and guava juices, 1.875 μL/mL MSEO or 15 μL/mL MVEO caused ≥5-log reductions in counts of P. anomala and S. cerevisiae. In pineapple juice, 3.75 μL/mL MSEO caused ≥5-log reductions in counts of P. anomala and S. cerevisiae; 15 μL/mL MVEO caused ≥5-log reductions in counts of S. cerevisiae in mango juice. The incorporation of 1.875 μL/mL MSEO did not affect the physicochemical parameters of juices and did not induce negative impacts to cause their possible sensory rejection. These results show the potential of MSEO and MVEO, primarily MSEO, to comprise strategies to control spoilage yeasts in fruit juices.

Storage Stability of Dietary Nitrate and Phenolic Compounds in Beetroot (Beta vulgaris) and Arugula (Eruca sativa) Juices

Nitrate and polyphenols from the diet may enhance the production and bioavailability of nitric oxide, a radical signaling molecule critical for cardiovascular health. Understanding the stability of these bioactives in beetroot and arugula juices is important for their functions. In this study, the stability of nitrate and phenolics in beetroot and arugula juices was measured for 32 days at different temperatures (25, 4, -20, and -80 °C). The levels of nitrate were measured by reversed-phase HPLC and initial levels were found to be 4965.34 ± 72.69 μg/mL for beetroot and 6310.20 ± 24.79 μg/mL for arugula. Interestingly, nitrate degradation started within 24 hr at 25 °C and after 4 days at 4 °C. At -20 °C and -80 °C, nitrate levels remained stable for one month. Total phenolics and free radical scavenging activity varied significantly during storage conditions. Beetroot juice at 25 °C, significant decrease in total phenolics and antioxidant activity was observed, whereas at 4, -20 and -80 °C, the levels remained relatively stable. By contrast, arugula juice at 25 and 4 °C, an increase in total phenolics and antioxidant activity were observed after one month. Furthermore, UPLC-HR-QTOF-MS analysis demonstrated that flavonoid glucosides were converted to their aglycones and lower phenolics, resulting in higher total phenolics and antioxidant activity during storage. In conclusion, beetroot and arugula juices required frozen conditions for long-term storage to prevent degradation of nitrate and to maintain their nutritional value.

PRACTICAL APPLICATION

Beetroot and arugula juices have health-beneficial compounds such as nitrate and phenolics. Understanding the proper storage conditions can allow consumers to make informed choices that can help fresh juices to maintain their health promoting properties.

Influence of fruit juice processing on anthocyanin stability

Anthocyanins are quality determining compounds in red fruits and their corresponding juices. The fate of anthocyanins during production of juices is determined by countless factors and all of these need to be taken into consideration to optimize juice processes. Storage and pre-press procedures like freezing and thawing may influence the fruit's integrity and accordingly affects the extraction of valuable components during the subsequent mashing and pressing. Conventional thermal or novel non-thermal treatments to ensure microbial safety have both positive and negative effects on the anthocyanins. By inactivation of oxidizing enzymes, profiles and quantities of anthocyanins may be maintained, but more severe conditions may have adverse effects. To improve juice extraction and to increase yield, enzyme-assisted degradation of the cell walls is conducted. The applied enzyme preparations contain numerous side activities which also may degrade anthocyanins. Clarification and concentration will further reduce the final anthocyanin concentrations. Many studies have been published regarding evaluating individual fruits or single processing steps but, obviously, these results are not necessarily transferable. Accordingly, this review aims to summarize all relating studies comprehensively to the fate of anthocyanins during juice processing giving an overview of underlying mechanisms as well as the chemical and analytical background.

Effect of ultrasound treatment on visual color, vitamin C, total phenols, and carotenoids content in Cape gooseberry juice

Strong interest of consumers in acquiring minimally processed foods that conserve the different micronutrients has raised the need to study the effect of food processing methods on quality attributes. The aim of the study was to determine the effect ultrasound treatment on color, and the bioactive compounds (ascorbic acid, total phenols, carotenoids, and provitamin A) of Cape gooseberry juice. Color values, ascorbic acid, total phenols, carotenoids, and Retinol Activity Equivalent (RAE) were measured. The results indicate significant reductions (p<0.001) in the chromaticity, yellowing index (IY), and acid ascorbic content was observed in all the juice samples sonicated. But there were significant increases (p<0.001) in hue, the total color differences (TCD), total phenols, carotenoids, and RAE value as compared to control. The results demonstrated that ultrasound processing increase the availability of carotenoids, total phenols and RAE in Cape gooseberry juice.

The Effect of High Pressure Techniques on the Stability of Anthocyanins in Fruit and Vegetables

Anthocyanins are a group of phenolic compounds responsible for red, blue and violet colouration of many fruits, vegetables and flowers. The high content of these pigments is important as it influences directly their health promoting properties as well as the sensory quality of the product; however they are prone to degradation by, inter alia, elevated temperature and tissue enzymes. The traditional thermal methods of food preservation cause significant losses of these pigments. Thus, novel non-thermal techniques such as high pressure processing, high pressure carbon dioxide and high pressure homogenization are under consideration. In this review, the authors attempted to summarize the current knowledge of the impact of high pressure techniques on the stability of anthocyanins during processing and storage of fruit and vegetable products. Furthermore, the effect of the activity of enzymes involved in the degradation of these compounds has been described. The conclusions including comparisons of pressure-based methods with high temperature preservation techniques were presented.

Changes in the chemical properties and anti-oxidant activities of curcumin by microwave radiation

Curcumin is a dietary phenolic compound that has numerous beneficial health effects. In the present study, changes in the chemical properties and anti-oxidant activities of curcumin by microwave radiation were investigated. Degradation of curcumin dissolved in distilled water was accelerated according to the increase in radiation time or radiation intensity. Residual levels of curcumin after 5 min radiation at 500 W were 24-29%. Scavenging activities of curcumin against DPPH radical decreased by microwave radiation; those of curcumin against ABTS and AAPH radicals and nitrite were rather significantly enhanced. Conventional heating at 95°C also increased scavenging activities of ABTS, AAPH, and nitrite of curcumin but to a lesser extent. Fluorescence intensity of curcumin increased by regular heating but decreased by microwave heating. Among curcuminoids, bisdemethoxycurcumin was most resistant under microwave radiation as compared to curcumin or demethoxycurcumin.